WO2011155546A1 - Alkyl-modified vinyl alcohol polymer, and composition, thickener, coating material for paper, coated paper, adhesive and film that contain same - Google Patents

Abstract

Provided is a novel alkyl-modified polyvinyl alcohol (PVA) which exhibits excellent thickening properties while maintaining high water solubility, and which exhibits high water resistance when hardened without requiring the use of a specific crosslinking agent. Also provided are a composition, a thickener, a coating material for paper, coated paper, an adhesive, and a film, each containing the alkyl-modified PVA. Disclosed is an alkyl-modified vinyl alcohol polymer which contains monomer units (a) represented by general formula (I) and which has a viscosity-average degree of polymerization of 200 to 5,000, a degree of saponification of 20 to 99.99mol%, and a content of the monomer units (a) of 0.05 to 5mol%. In general formula (I), R¹ is linear or branched C_8-29 alkyl; and R² is a hydrogen atom or C_1-8 alkyl.

Description

Alkyl-modified vinyl alcohol polymer, composition containing the same, thickener, paper coating agent, coated paper, adhesive and film

The present invention relates to a novel alkyl-modified vinyl alcohol polymer, and a composition containing the same, a thickener, a paper coating agent, a coated paper, an adhesive, and a film.

Vinyl alcohol polymers (hereinafter sometimes referred to as “PVA”) have excellent film-forming properties, interface properties, and strength properties as a few crystalline water-soluble polymers. For this reason, PVA occupies an important position as a raw material for thickeners, paper coating agents, adhesives, fiber processing agents, binders, emulsion stabilizers, films and fibers.

Furthermore, in order to improve specific performance in PVA, various modified PVAs by controlling crystallinity and introducing functional groups have been developed. Among the modified PVA, alkyl-modified PVA into which an alkyl group is introduced is known to exhibit an alkyl group (hydrophobic group) interaction in an aqueous solvent and increase the viscosity (Japanese Patent Laid-Open No. 55-47256). See the official gazette). The alkyl-modified PVA increases in viscosity as the alkyl group content increases. However, if the alkyl group content is too high, water solubility decreases. Thus, alkyl-modified PVA into which an ionic functional group has been introduced has been proposed for the purpose of increasing water solubility (Japanese Patent Laid-Open Nos. 58-15055, 59-78963, and Hei 8). -60137). Similarly, for the purpose of enhancing the performance as an emulsion stabilizer, a modified PVA having an alkyl group and an ionic functional group (carboxyl group) has been proposed (see JP-A-8-281092).

However, when an ionic functional group is introduced into the alkyl-modified PVA, when coexisting with a substance having the opposite ionicity, there is an inconvenience that the viscosity and storage stability are reduced due to the bond with this substance. Moreover, when the alkyl-modified PVA into which the ionic functional group is introduced is used as, for example, a film or an adhesive, the water resistance becomes insufficient due to the presence of the ionic functional group. There is also a disadvantage that the surface water repellency is lowered.

Further, as described above, since PVA is water-soluble, there is a problem that the water resistance of the obtained coating film is not sufficient particularly when drying at a low temperature. In order to improve this point, various improvements have been investigated for PVA or this composition. As a method for increasing the water resistance, for example, a method of crosslinking PVA with glyoxal, glutaraldehyde, dialdehyde starch, a water-soluble epoxy compound, a methylol compound or the like is known. However, in order to sufficiently ensure the water resistance of the coating film obtained by this method, it is necessary to perform heat treatment for a long time at a high temperature of 100 ° C. or higher, particularly 120 ° C. or higher.

Also, as a method for making a PVA coating water resistant by low temperature drying, it is also known that the PVA aqueous solution is subjected to strong acid conditions such as pH 2 or lower. However, in this case, there is a disadvantage that the viscosity stability of the aqueous PVA solution is lowered and gelation occurs during use, and the water resistance of the obtained coating film is not sufficient.

Furthermore, a method of crosslinking a carboxyl group-containing PVA with a polyamide epichlorohydrin resin, a method of crosslinking an acetoacetyl group-containing PVA with a polyvalent aldehyde compound such as glyoxal, a polyfunctional epoxy compound, a polyfunctional carboxy compound, or a boron compound A method of crosslinking (see JP 2010-111969 A) and the like are also being studied. However, when the crosslinking agent used in each of these methods is used, there are disadvantages such as a decrease in viscosity stability of the PVA aqueous solution (coating agent).

On the other hand, an adhesive mainly composed of PVA is inexpensive and has excellent adhesiveness, and is used for bonding paperboard, corrugated paper, paper tube, paper, wallpaper, wood, and the like. Adhesives in which various emulsions and PVA are mixed are used for woodworking, fiber processing, paper adhesives, and the like. Thus, the water-based adhesive containing PVA (PVA-based water-based adhesive) is used for a wide range of applications. However, even with PVA-based water-based adhesives, further improvements such as adhesiveness including initial adhesiveness and storage stability (viscosity stability and dispersion stability) are available to cope with recent high-speed coating. Is required.

Among these, (1) an adhesive mainly composed of PVA, clay and a water-soluble boron compound (see JP-A-62-195070), (2) a PVA adhesive containing a specific metal salt ( (See JP-A-4-239085), (3) an adhesive containing modified polyvinyl alcohol containing 1 to 20 mol% of ethylene units, starch and saccharides (see JP-A-11-21530), and (4) molecules An adhesive containing a vinyl alcohol polymer having an 1,2-glycol bond of 1.8 to 3.5 mol% and a saponification degree of 90 mol% or more and an inorganic filler (Japanese Patent Laid-Open No. 2001-164219) No. gazette) has been proposed.

The adhesive (1) can improve the initial adhesiveness and is widely used industrially in the production of corrugated paper. However, the use of boron compounds, whose environmental impact is a concern, has been restricted in recent years, and there is a strong demand for alternatives. Similarly, many attempts have been made to improve initial adhesiveness by using a compound that can be a PVA crosslinking agent (for example, urea-formalin resin). However, there are cases where there is a concern about the safety of the compound used as a cross-linking agent substantially, and the viscosity stability of the composition is often insufficient.

In addition, although the adhesive of the above (2) has improved initial adhesiveness, it has a problem in storage stability and is not sufficiently satisfactory industrially. Furthermore, although the adhesives (3) and (4) have improved adhesiveness and storage stability to some extent, they do not sufficiently meet the recent demand for high-speed coating.

These PVA-based adhesives may be used by mixing with various emulsions as described above for the purpose of improving adhesiveness by increasing the solid content concentration, etc., but even in such adhesives, Improvement of the above performance (adhesiveness, storage stability, etc.) is desired.

JP 55-47256 A JP 58-15055 A JP 59-78963 A JP-A-8-60137 Japanese Patent Laid-Open No. 8-281092 JP 2010-111969 A JP-A-62-195070 JP-A-4-239085 Japanese Patent Laid-Open No. 11-21530 JP 2001-164219 A

The present invention has been made on the basis of the circumstances as described above, can exhibit excellent viscosity while maintaining high water solubility, and has high water resistance in a cured state without using a special crosslinking agent. It is an object to provide a novel alkyl-modified PVA which can have Another object of the present invention is to provide a composition, a thickener, a paper coating agent, a coated paper, an adhesive, and a film containing the alkyl-modified PVA.

The alkyl-modified PVA of the present invention made to solve the above problems is
The monomer unit (a) represented by the following general formula (I) is contained, the viscosity average polymerization degree is 200 or more and 5,000 or less, the saponification degree is 20 mol% or more and 99.99 mol% or less. The content rate of a body unit (a) is 0.05 mol% or more and 5 mol% or less.

(In formula (I), R ¹ represents a linear or branched alkyl group having 8 to 29 carbon atoms. R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

According to the alkyl-modified PVA, the presence of the hydrophobic R ¹ and the hydrophilic amide bond of the monomer unit (a) can exhibit excellent thickening while maintaining water solubility. . In addition, the alkyl-modified PVA has the monomer unit (a), and thus has high water resistance in the cured state (hereinafter, the water resistance in the cured state may be simply referred to as water resistance). be able to. Furthermore, in the said alkyl modified PVA, the said characteristic can be improved by making the viscosity average polymerization degree, the saponification degree, and the content rate of the said monomer unit (a) into the said range. Therefore, the alkyl-modified PVA can be suitably used for, for example, a thickener, a paper coating agent, an adhesive, and a film.

R ¹ in the above formula (I) is preferably a linear or branched alkyl group having 15 to 26 carbon atoms. Thus, by using a long-chain alkyl group for R ¹ , the above-described thickening and water resistance can be further enhanced.

The saponification degree of the alkyl-modified PVA is preferably 60 mol% or more and 99.9 mol% or less. By setting it as such a saponification degree, the interaction of the hydrophobic groups of the said alkyl modified PVA is expressed more effectively, for example, water resistance can be improved.

The alkyl-modified PVA may be obtained by saponifying a copolymer of an unsaturated monomer represented by the following general formula (II) and a vinyl ester monomer.

(In formula (II), the definitions of R ¹ and R ² are the same as in formula (I) above.)

In the alkyl-modified PVA, the content of the monomer unit (b) having a carboxyl group is preferably less than 0.1 mol%. Thus, the water resistance etc. of the said alkyl-modified PVA can be more effectively exhibited by making low the content rate of the monomer unit (b) which has a carboxyl group.

The composition of the present invention contains the alkyl-modified PVA. Since the composition contains the alkyl-modified PVA of the present invention, it can be suitably used as a thickener, a paper coating agent, an adhesive, a film, a paint, a binder, a fiber paste, and the like.

The composition further contains water and an oil component, and the content of the alkyl-modified PVA with respect to 100 parts by mass of the oil component is preferably 0.1 parts by mass or more and 50 parts by mass or less. The composition has a high viscosity and is excellent in storage stability.

The thickener of the present invention contains the alkyl-modified PVA. Since the thickener contains the alkyl-modified PVA, it can exhibit an excellent thickening function even when used in a small amount.

The thickener may further contain water or a water-containing solvent. Such a thickener can be suitably used as a liquid thickener.

The paper coating agent of the present invention contains the alkyl-modified PVA. According to the paper coating agent, since the alkyl-modified PVA is contained, the strength and water resistance of the coating film obtained by coating on the paper surface can be increased without using a special crosslinking agent. . Although this reason is not certain, for example, it is considered to be caused by drying in a state where the alkyl groups (R ¹ ) in the monomer unit (a) are associated with each other.

The coated paper of the present invention is obtained by coating the paper coating agent on the paper surface. The coated paper is excellent in surface strength, water resistance, and the like because the paper coating agent is coated on the surface.

The adhesive of the present invention contains the alkyl-modified PVA. Since the adhesive contains the alkyl-modified PVA, the adhesive has excellent initial adhesiveness and storage stability. The reason for this is not clear, but, for example, the alkyl group (R ¹ ) in the monomer unit (a) is associated with each other to serve as a cross-linking agent, and as a result, the initial adhesiveness is increased. In addition, it is conceivable that the storage stability is improved due to the balance between the new aqueous property and the hydrophobicity derived from the structure of the monomer unit (a).

The adhesive preferably further contains, in an emulsion state, a polymer obtained from at least one monomer selected from the group consisting of ethylenically unsaturated monomers and diene monomers. By using the adhesive mixed with such a polymer emulsion, it is possible to further improve the drying property and the strength after adhesion while exhibiting excellent initial adhesiveness and storage stability.

It is preferable that the adhesive further contains a filler. The adhesive can further increase the drying property, strength after bonding, and the like by further including a filler.

The adhesive can be suitably used for paper or woodwork.

The film of the present invention contains the alkyl-modified PVA. Since the film contains the alkyl-modified PVA, it has excellent surface water repellency.

The contact angle of the film with water is preferably 70 ° or more. The film can exhibit more excellent surface water repellency by having such a high contact angle.

As described above, the alkyl-modified PVA of the present invention can exhibit excellent thickening properties while maintaining high water solubility, and has high water resistance in a cured state without using a special crosslinking agent. it can. Therefore, the alkyl-modified PVA can be suitably used for, for example, a thickener, a paper coating agent, an adhesive and a film.

Hereinafter, embodiments of the alkyl-modified PVA, the composition, the thickener, the paper coating agent, the coated paper, the adhesive, and the film of the present invention will be described in detail.

<Alkyl-modified PVA>
The alkyl-modified PVA contains a monomer unit (a) represented by the following general formula (I). That is, the alkyl-modified PVA is a copolymer of the monomer unit (a) and a vinyl alcohol monomer unit (—CH ₂ —CHOH—), and further has other monomer units. It may be.

In the formula (I), R ¹ represents a linear or branched alkyl group having 8 to 29 carbon atoms. R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. The R ¹ and R ² may have a substituent such as a halogen atom as long as the effect of the present invention is not impaired, but preferably does not have these substituents. .

The linear or branched alkyl group represented by R ¹ has 8 to 29 carbon atoms, preferably 10 to 28, more preferably 12 to 27, and 15 to 26. More preferably, 17 or more and 24 or less are particularly preferable. When the number of carbon atoms is less than 8, the interaction between alkyl groups in the alkyl-modified PVA does not appear, so that high viscosity, water resistance, adhesiveness, surface water repellency when formed into a film, and the like are not sufficiently exhibited. On the contrary, when this carbon number exceeds 29, the water solubility etc. of the said alkyl-modified PVA fall.

R ² is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and is preferably a hydrogen atom or a methyl group from the viewpoint of ease of synthesis.

The content of the monomer unit (a) in the alkyl-modified PVA is 0.05 mol% or more and 5 mol% or less. Further, the content is preferably 0.1 mol% or more, and more preferably 0.2 mol% or more. Further, the content is preferably 2 mol% or less, and more preferably 1 mol% or less. In addition, the content rate of this monomer unit (a) is a content rate of the monomer unit (a) represented by the said Formula (I) which occupies for all the structural units which comprise the alkyl-modified PVA. When the alkyl-modified PVA does not contain any other alkyl-modified monomer unit other than the monomer unit (a) represented by the above formula (I), the content of the monomer unit (a) Is the so-called alkyl modification rate.

When the content of the monomer unit (a) exceeds 5 mol%, the proportion of hydrophobic groups contained in one molecule of the alkyl-modified PVA increases, and the water solubility of the alkyl-modified PVA decreases. On the other hand, when the content of the monomer unit (a) is less than 0.05 mol%, the water content of the alkyl-modified PVA is excellent, but the number of alkyl units contained in the alkyl-modified PVA is small. Further, physical properties based on alkyl modification such as thickening, water resistance, adhesiveness, storage stability, strength when formed into a coating film, and surface water repellency when formed into a film are not sufficiently exhibited.

The content of the monomer unit (a) can be determined from proton NMR of an alkyl-modified vinyl ester polymer that is a precursor of the alkyl-modified PVA. Specifically, after reprecipitation purification of the alkyl-modified vinyl ester polymer with n-hexane / acetone three or more times, it is dried under reduced pressure at 50 ° C. for 2 days to prepare a sample for analysis. To do. This sample is dissolved in CDCl ₃ and measured at room temperature using 500 MHz proton NMR (JEOL GX-500).

In this case, for example, when the alkyl-modified monomer unit other than the monomer unit (a) is not included, R ¹ is linear, and R ² is a hydrogen atom, the calculation is performed by the following method. it can. That is, the peak α (4.7 to 5.2 ppm) derived from the main chain methine of the alkyl-modified vinyl ester polymer and the peak β (0.8 to 1.0 ppm) derived from the terminal methyl group of the alkyl group R ¹ From the above, the content S of the monomer unit (a) is calculated using the following formula.
S (mol%)
= {(Number of protons of β / 3) / (number of protons of α + (number of protons of β / 3))} × 100

The content of the monomer unit (b) having a carboxyl group in the alkyl-modified PVA is preferably less than 0.1 mol%, and more preferably 0.01 mol% or less. When the content of the monomer unit (b) is 0.1 mol% or more, the adhesiveness, water resistance, storage stability, strength when formed into a coating film, or the like is decreased or hydrophilic when formed into a film. May increase and the contact angle may decrease. In addition, the content rate of this monomer unit (b) is a content rate of this monomer unit (b) in all the structural units which comprise alkyl-modified PVA, and monomer unit (a) mentioned above Similarly to the content ratio, it can be determined from proton NMR.

The viscosity average polymerization degree of the alkyl-modified PVA is 200 or more and 5,000 or less. The viscosity average degree of polymerization may be simply referred to as the degree of polymerization. If the degree of polymerization exceeds 5,000, the productivity of the alkyl-modified PVA is lowered, which is not practical. On the other hand, when the degree of polymerization is less than 200, each characteristic of the alkyl-modified PVA such as thickening, water resistance, initial adhesiveness, strength when formed into a coating film or a film may not be sufficiently exhibited. The lower limit of the degree of polymerization is preferably 500 and more preferably 1,000 from the viewpoint of increasing the strength of the coating film or film containing the alkyl-modified PVA.

This viscosity average degree of polymerization (P) is measured according to JIS-K6726. That is, after re-saponifying and purifying the alkyl-modified PVA, it is obtained by the following formula from the intrinsic viscosity [η] (unit: deciliter / g) measured in water at 30 ° C.
P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

The saponification degree of the alkyl-modified PVA needs to be 20 mol% or more and 99.99 mol% or less, and preferably 40 mol% or more and 99.9 mol% or less. Among these, when water resistance is required, the saponification degree of the alkyl-modified PVA is more preferably 60 mol% or more and 99.9 mol% or less, and further preferably 70 mol% or more and 99.9 mol% or less. 80 mol% or more and 99.9 mol% or less is particularly preferable, and 96 mol% or more and 99.9 mol% or less is most preferable.

When the degree of saponification is less than 20 mol%, the water solubility and the like of the alkyl-modified PVA are lowered, and the association performance (crosslinking performance) expressed by the hydrophobic group interaction is lowered, thereby increasing the viscosity and water resistance. Property, adhesiveness, strength when formed into a coating film, and surface water repellency when formed into a film are also lowered. On the contrary, if the degree of saponification exceeds 99.99 mol%, production of alkyl-modified PVA becomes difficult, which is not practical. The saponification degree of the alkyl-modified PVA is a value that can be measured according to JIS-K6726.

According to the alkyl-modified PVA, as described above, due to the presence of the hydrophobic R ¹ and the hydrophilic amide bond of the monomer unit (a), excellent thickening and the like while maintaining water solubility. Can be demonstrated. Moreover, the said alkyl modified PVA can have high water resistance in the hardened state by having the said monomer unit (a). Furthermore, in the said alkyl modified PVA, the said characteristic can be improved by making the viscosity average polymerization degree, the saponification degree, and the content rate of the said monomer unit (a) into the said range. Therefore, the alkyl-modified PVA can be suitably used for, for example, a thickener, a paper coating agent, an adhesive, and a film.

<Method for producing alkyl-modified PVA>
The method for producing the alkyl-modified PVA is not particularly limited, but the alkyl-modified vinyl ester obtained by copolymerizing an unsaturated monomer represented by the following general formula (II) and a vinyl ester monomer. A method of saponifying the polymer is preferred. Here, the above copolymerization is preferably performed in an alcohol solvent or without a solvent.

In the formula (II), the definitions of R ¹ and R ² are the same as those in the above formula (I).

Specific examples of the unsaturated monomer represented by the above formula (II) include N-octylacrylamide, N-decylacrylamide, N-dodecylacrylamide, N-octadecylacrylamide, N-hexacosylacrylamide, and N-octyl. Examples include methacrylamide, N-decyl methacrylamide, N-dodecyl methacrylamide, N-octadecyl methacrylamide, N-hexacosyl methacrylamide and the like. Among these, N-octadecyl acrylamide, N-octyl methacrylamide, N-decyl methacrylamide, N-dodecyl methacrylamide, N-octadecyl methacrylamide, and N-hexacosyl methacrylamide are preferable, and N-octadecyl acrylamide, N -Dodecyl methacrylamide and N-octadecyl methacrylamide are more preferred, and N-octadecyl acrylamide and N-octadecyl methacrylamide are more preferred.

Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, and vinyl palmitate. , Vinyl stearate, vinyl oleate, vinyl benzoate and the like, among which vinyl acetate is preferred.

When the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer are copolymerized, other monomers may be copolymerized within a range not impairing the gist of the present invention. Examples of monomers that can be used include:
Α-olefins such as ethylene, propylene, n-butene and isobutylene;
Vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane;
Nitriles such as acrylonitrile and methacrylonitrile;
Vinyl halides such as vinyl chloride and vinyl fluoride;
Vinylidene halides such as vinylidene chloride and vinylidene fluoride;
Allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride;
Vinylsilyl compounds such as vinyltrimethoxysilane;
And isopropenyl acetate.

In addition, in the copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer, the purpose of the present invention is to adjust the degree of polymerization of the obtained copolymer. Copolymerization may be carried out in the presence of a chain transfer agent within a range that does not impair. As this chain transfer agent,
Aldehydes such as acetaldehyde and propionaldehyde;
Ketones such as acetone and methyl ethyl ketone;
Mercaptans such as 2-hydroxyethanethiol;
Halogenated hydrocarbons such as trichlorethylene and perchlorethylene;
Examples thereof include phosphinic acid salts such as sodium phosphinate monohydrate, among which aldehydes and ketones are preferably used.

The amount of the chain transfer agent added can be determined according to the chain transfer constant of the chain transfer agent to be added and the degree of polymerization of the target alkyl-modified vinyl ester polymer. The content is preferably 0.1 to 10% by mass.

The temperature employed when copolymerizing the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is preferably 0 to 200 ° C, more preferably 30 to 140 ° C. When the copolymerization temperature is lower than 0 ° C., it is difficult to obtain a sufficient polymerization rate. Moreover, when the temperature which superposes | polymerizes is higher than 200 degreeC, it is difficult to obtain the alkyl modified PVA which satisfies the content rate of the monomer unit (a) prescribed | regulated by this invention. As a method for controlling the temperature employed in the copolymerization to 0 to 200 ° C., for example, by controlling the polymerization rate, the heat generated by the polymerization is balanced with the heat released from the surface of the reactor. Examples thereof include a method and a method of controlling by an external jacket using an appropriate heat medium, but the latter method is preferable from the viewpoint of safety.

The polymerization method employed for the copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is batch polymerization, semi-batch polymerization, continuous polymerization, or semi-continuous polymerization. Either of these may be used. As the polymerization method, any known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method can be employed. Among these, a bulk polymerization method or a solution polymerization method in which polymerization is performed in a solvent-free or alcohol-based solvent is preferably employed, and an emulsion polymerization method is employed for the purpose of producing a copolymer having a high degree of polymerization. .

As the alcohol solvent, methanol, ethanol, n-propanol or the like can be used, but is not limited thereto. Moreover, these solvents can be used by mixing two or more kinds.

As the initiator used for copolymerization, conventionally known azo initiators, peroxide initiators, redox initiators and the like are appropriately selected according to the polymerization method. Examples of the azo initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4- Dimethyl valeronitrile) and the like, and peroxide initiators include perisopropyl compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, diethoxyethyl peroxydicarbonate; t-butyl Perester compounds such as peroxyneodecanate, α-cumylperoxyneodecanate, and t-butylperoxydecanate; acetylcyclohexylsulfonyl peroxide; 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, etc. Is mentioned. Furthermore, the initiator can be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like to form an initiator. Examples of the redox initiator include a combination of the above-described peroxide and a reducing agent such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, Rongalite and the like.

In addition, when copolymerization of the unsaturated monomer represented by the general formula (II) and the vinyl ester monomer is performed at a high temperature, the coloring of the alkyl-modified PVA caused by the decomposition of the vinyl ester monomer Etc. may be seen. In this case, an antioxidant such as tartaric acid may be added to the polymerization system in an amount of 1 to 100 ppm with respect to the vinyl ester monomer for the purpose of preventing coloring.

In the saponification reaction of the alkyl-modified vinyl ester polymer obtained by the above copolymerization, a basic catalyst such as sodium hydroxide, potassium hydroxide or sodium methoxide or an acidic catalyst such as p-toluenesulfonic acid is used. An alcoholysis reaction or a hydrolysis reaction can be applied. Examples of the solvent that can be used in this reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene and toluene; These can be used alone or in combination of two or more. Among these, it is simple and preferable to perform the saponification reaction using methanol or a methanol / methyl acetate mixed solution as a solvent and sodium hydroxide as a catalyst.

<Composition>
The composition of the present invention contains the alkyl-modified PVA. The composition may be a liquid containing the alkyl-modified PVA, a solvent or the like, or may be a solid obtained by curing the liquid composition by drying or the like. In addition, the thickener, paper coating agent, and the coating film obtained from it, an adhesive agent, and a film which are explained in full detail later are also contained in the said composition. Hereinafter, the case where the composition is in a liquid form will be described.

The solvent is not particularly limited, but is usually water, and may be an organic solvent such as alcohol described later. Moreover, the mixed solvent of water and an organic solvent may be sufficient.

The concentration of the alkyl-modified PVA in the liquid composition is not particularly limited. For example, when the solvent is water, the concentration can be 1% by mass or more and 10% by mass or less. According to the composition, since the alkyl-modified PVA has high water solubility, the concentration can be relatively high.

Since the liquid composition contains the alkyl-modified PVA, it is excellent in water resistance of a film obtained by, for example, forming a film and drying it. The water resistance of the film can be evaluated by immersing the film in distilled water at 20 ° C. for 24 hours and then measuring the dissolution rate of the film. The elution rate is preferably less than 20% by mass, more preferably less than 10% by mass, and even more preferably less than 5% by mass.

The liquid composition may contain various known crosslinking agents, plasticizers, surfactants, antifoaming agents, ultraviolet absorbers and the like as long as the effects of the present invention are not impaired.

The liquid composition is used in various applications where water resistance is required, such as paper coating agents (clear coating agents, pigment coating agents, internal sizing agents, thermal paper overcoat binders, etc.), binders, and adhesives. It can be suitably used as a fiber paste or the like.

The liquid composition may include water and oil in addition to the alkyl-modified PVA. The composition has a high viscosity and is excellent in storage stability.

The oil is usually present in an emulsion state dispersed in water. Such dispersions include aqueous polyacrylate dispersions, aqueous dispersions of olefinically unsaturated monomers alone or copolymers, aqueous polyvinyl acetate dispersions, aqueous polyurethane dispersions, aqueous polyester dispersions. And existing aqueous emulsion dispersions.

The content of the alkyl-modified PVA in such a composition is preferably 0.1 part by mass or more and 50 parts by mass or less, and more preferably 0.3 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of oil. By setting the content of the alkyl-modified PVA in the above range, both the viscosity and the storage stability of the composition can be exhibited in a well-balanced manner.

In order to increase the storage stability of this composition, it is preferable to relatively increase the degree of polymerization of the PVA and the content of the monomer unit (a).

<Thickener>
Since the thickener of this invention contains the said alkyl modified PVA, it can exhibit the outstanding thickening.

The thickening agent may be a powdery thickening agent made of the alkyl-modified PVA or a liquid thickening agent containing water or a water-containing solvent. This liquid thickener is suitable for use in water-dispersible emulsion-containing materials such as paints and adhesives.

The solvent other than water contained in the water-containing solvent is not particularly limited. For example, alcohol solvents such as methanol and ethanol; ester solvents such as methyl acetate and ethyl acetate; diethyl ether, 1,4-dioxane and methyl Ether solvents such as cellosolve, cellosolve, butyl cellosolve, MTBE (methyl-t-butyl ether) and butyl carbitol; ketone solvents such as acetone and diethyl ketone; glycol solvents such as ethylene glycol, propylene glycol, diethylene glycol and triethylene glycol Glycol ether solvents such as diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol; Chi glycol monomethyl ether acetate, PMA (propylene glycol monomethyl ether acetate), diethylene glycol monobutyl ether acetate, can be mentioned glycol esters solvents such as diethylene glycol monoethyl ether acetate.

When the thickener is in a liquid state, the amount of the alkyl-modified PVA is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass with respect to 100 parts by mass of the solvent. Such a liquid thickener is produced by adding the alkyl-modified PVA to water or a water-containing solvent and mixing them by heating.

In the liquid thickener, various plasticizers, surfactants, antifoaming agents, ultraviolet absorbers and the like may be blended as long as the effects of the present invention are not impaired.

Similarly, the thickener may be made of various other water-soluble polymers such as various known PVA, starch, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose as long as the effects of the present invention are not impaired. You may mix | blend. The blending amount of these other water-soluble polymers is preferably 50 parts by mass or less with respect to 100 parts by mass of the alkyl-modified PVA.

The thickener exhibits high viscosity in a small amount and exhibits stable viscosity. Therefore, the said thickener can be conveniently used as a thickener used for water-system solutions and water-system emulsion solutions, such as a paint, cement, concrete, a binder, an adhesive agent, and cosmetics.

<Paper coating agent>
The paper coating agent of the present invention contains the alkyl-modified PVA. The paper coating agent is usually an aqueous solution of the alkyl-modified PVA, and may contain other solvents and additives.

Although it does not specifically limit as the density | concentration of the said alkyl modified PVA in the said coating agent for paper, From points, such as applicability | paintability and the intensity | strength of a coating film obtained, and water resistance, 0.5 mass% as an alkyl modified PVA aqueous solution. The content is preferably 20% by mass or less and more preferably 1% by mass or more and 10% by mass or less.

Examples of the additive contained in the paper coating agent include fillers, various polymers, water resistance agents, pH adjusters, antifoaming agents, and surfactants.

Examples of the filler include kaolin, clay, calcined clay, calcium carbonate, titanium oxide, diatomaceous earth, aluminum oxide, aluminum hydroxide, synthetic aluminum silicate, synthetic magnesium silicate, polystyrene fine particles, polyvinyl acetate fine particles, urea- Formalin resin fine particles, precipitated silica, gel silica, silica synthesized by gas phase method (hereinafter referred to as gas phase method silica), colloidal silica, colloidal alumina, pseudoboehmite, talc, zeolite, alumina, zinc oxide, satin Examples include white and organic pigments.

Examples of the polymer include various modified PVAs such as non-modified PVA, sulfonic acid group-modified PVA, acrylamide-modified PVA, cation group-modified PVA, and long-chain alkyl group-modified PVA, and water-soluble substances such as starch, modified starch, casein, and carboxymethyl cellulose. And a synthetic resin emulsion such as a conductive polymer, styrene-butadiene latex, polyacrylate emulsion, vinyl acetate-ethylene copolymer emulsion, vinyl acetate-acrylate copolymer emulsion, and the like.

The solid content concentration in the paper coating agent is not particularly limited and can be appropriately adjusted according to the use. However, in consideration of applicability, the mass content is preferably 1% by mass to 65% by mass, and preferably 1% by mass. % To 40% by mass is more preferable, 1% to 20% by mass is more preferable, and 2% to 15% by mass is particularly preferable.

The paper coating agent can be suitably used for applications requiring water resistance such as an overcoat layer of thermal paper, for example. In this case, the content of the additive typified by the filler is preferably 50 parts by mass or more and 150 parts by mass or less, and more preferably 80 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the alkyl-modified PVA. . In addition, the solid content concentration of the paper coating agent (overcoat layer coating material) can be appropriately adjusted, for example, in the range of 10% by mass to 65% by mass.

The paper coating agent is also preferably used as a filler binder such as an ink receiving layer binder for ink jet recording paper. In this case, the paper coating agent preferably contains the filler as an additive. At this time, the content ratio of the filler such as silica and the alkyl-modified PVA is not particularly limited, but the alkyl-modified PVA is 3 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the filler. Is preferably 5 to 40 parts by mass, more preferably 10 to 30 parts by mass.

The paper coating agent can also be used as a barrier agent, for example. Also in this case, the above additives can be appropriately contained and used. The content of additives typified by fillers and antifoaming agents is not particularly limited, but is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the alkyl-modified PVA. More preferred is 5 parts by mass or more. Moreover, the solid content concentration of the paper coating agent can be appropriately adjusted within a range of, for example, 1% by mass to 20% by mass.

The method for coating the paper coating agent on the paper surface is not particularly limited, and a known coater (size press coater, air knife coater, blade coater, roll coater, etc.) may be used. After coating on the paper surface, an optional step such as a drying step or a calendar step may be performed as necessary.

<Coated paper>
The coated paper of the present invention is obtained by coating the paper coating agent on the paper surface. The coated paper is excellent in surface strength and water resistance since the paper coating agent is coated on the surface. The coated paper can be produced by a known method. The coated paper can be suitably used as, for example, thermal paper, ink jet recording paper, release paper base paper, and the like.

<Adhesive>
The adhesive of the present invention contains the alkyl-modified PVA. The adhesive is usually an aqueous solution of the alkyl-modified PVA and may contain other additives.

Although it does not specifically limit as the density | concentration of the said alkyl modified PVA in the said adhesive agent, From points, such as applicability | paintability, adhesiveness, the intensity | strength of an adhesion part, and water resistance, 0.5 mass% or more and 20 mass as an alkyl modified PVA aqueous solution. % Or less is preferable, and 1 mass% or more and 10 mass% or less are more preferable.

The alkyl-modified PVA contained in the adhesive is considered to form a pseudo-aggregate by hydrophobic group interaction between specific alkyl groups (R ¹ ) in water. This is considered to exhibit an important characteristic for the expression of initial adhesive force such as a high viscosity and a large thickening behavior as the concentration increases, and improve storage stability such as dispersion stability and sedimentation stability of the filler. Furthermore, it is considered that the specific alkyl group (R ¹ ) forms a pseudo-aggregate and is dried to improve the water-resistant adhesion.

In order to further improve the water-resistant adhesion in the adhesive, it is preferable to increase the degree of saponification of the alkyl-modified PVA or decrease the content of the monomer unit (b).

The adhesive can contain an emulsion polymer or filler in addition to the alkyl-modified PVA. Furthermore, the adhesive may contain other additives. Other additives include metal salts of phosphate compounds such as sodium polyphosphate and sodium hexametaphosphate and inorganic dispersants such as water glass; polyacrylic acid and its salts, sodium alginate, α-olefin-maleic anhydride Anionic polymer compounds such as polymers and metal salts thereof; Nonionic surfactants such as polyethylene oxide, ethylene oxide adducts of higher alcohols, copolymers of ethylene oxide and propylene oxide; Cellulose derivatives such as carboxymethyl cellulose and methyl cellulose Other examples include antifoaming agents, antiseptics, antifungal agents, colored pigments, deodorants, and fragrances.

The adhesive contains the polymer in an emulsion state, whereby the adhesiveness can be improved and the load during drying due to an increase in solid content can be reduced. The polymer contained in the emulsion state (hereinafter also referred to as polymer emulsion) is not particularly limited, but is at least one unit selected from the group consisting of ethylenically unsaturated monomers and diene monomers. A polymer (including a copolymer) obtained from a monomer is preferred.

Examples of the ethylenically unsaturated monomer include olefins such as ethylene, propylene, and isobutylene, vinyl esters such as vinyl acetate, (meth) acrylic acid esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, styrene, and the like. Can be mentioned.

Further, examples of the diene monomer include butadiene, isoprene, chloroprene and the like.

As such a polymer emulsion, specifically,
Vinyl acetate emulsions such as vinyl acetate polymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl versatate copolymer, vinyl acetate- (meth) acrylate copolymer;
(Meth) acrylate emulsions such as methyl methacrylate / n-butyl acrylate copolymer;
Styrene emulsion;
Examples thereof include butadiene-based emulsions such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer.

Among these, vinyl acetate emulsion particles or (meth) acrylic ester emulsion particles are preferable from the viewpoint of initial adhesiveness and storage stability of the adhesive.

The emulsion particles of the above polymer can be added together with the dispersion stabilizer to enhance the stability of the emulsion state. As the dispersion stabilizer, a vinyl alcohol polymer, a water-soluble cellulose derivative such as hydroxyethyl cellulose, various surfactants, and the like can be used, and among them, a vinyl alcohol polymer is preferable.

The content of these emulsions (polymer emulsion particles and dispersion stabilizer) is usually 1,000 parts by weight or less, preferably 700 parts by weight or less, more preferably 100 parts by weight or less based on 100 parts by weight of the alkyl-modified PVA on a solid basis. 500 parts by mass or less and 100 parts by mass or more can be used.

The adhesive further contains a filler, thereby reducing the load during drying due to an increase in solid content and improving the strength and hardness after bonding.

As the filler,
Inorganic fillers such as kaolinite, halloysite, pyroferrite or sericite clay, heavy, light or surface treated calcium carbonate, aluminum hydroxide, aluminum oxide, gypsum, talc, titanium oxide;
Examples thereof include organic fillers such as starch, oxidized starch, wheat flour and wood flour. Among these, various clays and various starches can be suitably used.

The content of the filler is preferably 1,000 parts by mass or less, more preferably 500 parts by mass or less, and still more preferably 400 parts by mass or less and 50 parts by mass or more with respect to 100 parts by mass of the alkyl-modified PVA on a solid basis. When the content of the filler exceeds the upper limit, sedimentation of the filler occurs during storage, and storage stability may decrease.

The method for preparing the adhesive is not particularly limited, and a known method can be used. For example, a premixed mixture of alkyl-modified PVA and other additives such as filler is added to water while stirring, or various additives, filler, and alkyl-modified PVA are sequentially added to water while stirring. Examples of the method include preparing a slurry liquid and then dissolving it by heating. As a heating method at this time, a known heating method such as a heating method in which steam is directly blown into the slurry liquid or an indirect heating method using a jacket can be employed. This preparation may be carried out either batchwise or continuously.

The adhesive is excellent in storage stability such as viscosity stability and sedimentation stability in addition to water solubility and initial adhesiveness. Moreover, the water resistance after adhesion | attachment can also be improved by adjusting the alkyl modified PVA to contain. Therefore, the water-soluble adhesive is a paper adhesive used in the production or use of corrugated paper, paper bags, paper boxes, paper tubes, wallpaper, etc., wood-to-wood, wood-to-fiber, wood-to-paper, wood-to-plastic. It is preferably used as an adhesive for woodworking to bond the steel. Further, it can also be used for applications using fibers such as cloth and non-woven fabric, cement moldings such as concrete, various plastics, aluminum foil, and the like. In addition, the use of the adhesive agent of this invention is not limited to these.

The viscosity of the adhesive can be arbitrarily selected depending on the application. When high-speed coating properties are intended, the viscosity at the bonding temperature is preferably 100 to 10,000 mPa · s in terms of B-type viscosity.

<Film>
The film of the present invention contains the alkyl-modified PVA. Since the film contains the alkyl-modified PVA, the film can have high surface water repellency.
The content of the alkyl-modified PVA in the film is usually 50% by mass or more, and more preferably 90% by mass or more. By setting the content of the alkyl-modified PVA in the above range, the water repellency of the film can be effectively expressed.

The film may contain various known plasticizers, surfactants, antifoaming agents, ultraviolet absorbers and the like as long as the effects of the present invention are not impaired.

Similarly, the film contains various other water-soluble polymers such as various known PVA, starch, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, etc., as long as the effects of the present invention are not impaired. You may do it. The blending amount of these other water-soluble polymers in the film is preferably 50 parts by mass or less with respect to 100 parts by mass of the alkyl-modified PVA.

The contact angle of the film with water is preferably 70 ° or more, more preferably 80 ° or more, and still more preferably 85 ° or more. In the film, when the contact angle with water is less than 70 °, high surface water repellency may not be exhibited.

As a manufacturing method of the film, for example,
(1) A method of forming a film of the water-containing alkyl-modified PVA by a melt extrusion method,
(2) Using a film-forming stock solution in which the alkyl-modified PVA is dissolved in a solvent, a casting film-forming method, a wet film-forming method (discharging into a poor solvent), a gel film-forming method (cooling the solution once to gelation) Then, the solvent is extracted and removed to obtain a film) and a combination thereof.
Among these production methods, the casting film forming method and the melt extrusion film forming method are preferable because a good film can be obtained.

Examples of the solvent used to dissolve the alkyl-modified PVA used in producing the film of the present invention include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, Examples include tetraethylene glycol, trimethylolpropane, ethylenediamine, diethylenetriamine, glycerin, methanol, ethanol, propanol, water, and the like, and one or more of these can be used. Among these, water or a mixed solvent of water and glycerin is preferably used.

The film containing the alkyl-modified PVA has such a high surface water repellency and can be suitably used as, for example, various water-repellent coating materials, surface coating materials, and the like.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. In the following examples and comparative examples, “part” and “%” mean mass basis unless otherwise specified.

The obtained PVA (alkyl-modified PVA and non-modified PVA) was evaluated according to the following method.

[Modification rate]
The content of the monomer unit (a) represented by the formula (I) in PVA (hereinafter also referred to as “alkyl modification rate”) and the content of the monomer unit (b) having a carboxyl group (hereinafter, Each modification rate including “itaconic acid modification rate” was determined according to the above-described method using proton NMR.

[Degree of polymerization]
The degree of polymerization of PVA was determined by the method described in JIS-K6726.

[Saponification degree]
The degree of saponification of PVA was determined by the method described in JIS-K6726.

[Water soluble]
4 g of PVA was added to 96 g of distilled water at room temperature and stirred for 30 minutes. The obtained PVA aqueous solution was heated to 90 ° C., stirred as it was for 1 hour, cooled to room temperature, and filtered using a 105 mmφ wire mesh. After filtration, the wire mesh was dried at 105 ° C. for 3 hours, cooled to room temperature in a desiccator, the mass was measured, and the mass of the wire mesh increased before and after filtration was determined. The mass of the wire mesh increased after filtration was defined as a (g), and the insoluble content (%) was calculated according to the following formula. In the formula used to calculate the insoluble content, the pure content (%) is a value obtained using the following formula.
Pure content (%) = {mass of PVA dried at 105 ° C. for 3 hours (g) / mass of PVA before drying (g)} × 100
Insoluble content (%) = {a (g) / 4 (g)} × {100 / pure content (%)} × 100
The insoluble content (%) calculated according to the above formula was determined according to the following criteria.
A: Less than 0.01% B: 0.01% or more and less than 0.1% C: 0.1% or more and less than 0.5% D: 0.5% or more and less than 1.0% E: 1.0% or more

[Water resistance of coating made of PVA]
A PVA aqueous solution having a concentration of 4% was prepared and cast on a polyethylene terephthalate (PET) film at 20 ° C. to obtain a film having a thickness of 40 μm. The obtained film was cut into a size of 5 cm in length and 5 cm in width to produce a test piece, and the mass (mass A) was measured. This test piece was immersed in distilled water at 20 ° C. for 24 hours and then collected, and moisture adhering to the surface was wiped off with gauze and dried at 105 ° C. for 16 hours, and then the mass (mass B) was measured. The water content of the film before immersion was C (mass%), the dissolution rate (%) was determined according to the following formula, and the determination was made according to the following criteria. The moisture content of the film before dipping was obtained in advance by drying the separately cut film before dipping at 105 ° C. for 4 hours.
Elution rate (%) = [1-B / {(1-C / 100) × A}] × 100
A: Less than 5.0% B: 5.0% or more and less than 10.0% C: 10.0% or more and less than 20.0% D: 20.0% or more, or the test piece is dissolved and cannot be recovered It was.

Example 1 (Production of PVA1)
A 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, comonomer addition port and initiator addition port was charged with 750 g of vinyl acetate, 250 g of methanol and 1.1 g of N-octadecyl methacrylamide and subjected to nitrogen bubbling. Then, the system was purged with nitrogen for 30 minutes. Further, a comonomer solution having a concentration of 5% was prepared by dissolving N-octadecylmethacrylamide in methanol as a delay solution, and this comonomer solution was purged with nitrogen by bubbling nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. The delay solution was added dropwise to the reactor so that the monomer composition in the polymerization solution was constant, and polymerization was performed at 60 ° C. for 3 hours, followed by cooling to stop the polymerization. The total amount of comonomer added until the polymerization was stopped was 4.8 g. The solid content concentration when the polymerization was stopped was 29.9%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 35%) of an alkyl-modified vinyl acetate polymer (alkyl-modified PVAc). Further, 777.9 g of alkyl-modified PVAc methanol solution prepared by adding methanol (200.0 g of alkyl-modified PVAc in the solution) was added to 27.9 g of an alkali solution (sodium hydroxide in 10% methanol). Saponification was performed by adding. Here, the concentration of the alkyl-modified PVAc in the saponification solution was 25%, and the molar ratio of sodium hydroxide to the vinyl acetate unit in the alkyl-modified PVAc was 0.03. A gel was formed about 1 minute after the addition of the alkaline solution. The gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, 500 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. To this white solid, 2,000 g of methanol was added, and the mixture was left to wash at room temperature for 3 hours. This washing operation was repeated three times, and then the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain alkyl-modified PVA (PVA1).

Examples 2 to 15 and Comparative Examples 1 to 5 (Production of PVA 2 to 15 and PVA i to v)
Charge amount of vinyl acetate and methanol, polymerization conditions such as kind and addition amount of unsaturated monomer having alkyl group used during polymerization, concentration of alkyl-modified PVAc during saponification, molar ratio of sodium hydroxide to vinyl acetate unit Various alkyl-modified PVAs (PVA2 to 15 and PVAi to v) were produced in the same manner as in Example 1 except that the saponification conditions such as the above were changed as shown in Table 1.

Example 16 (Production of PVA16)
In a 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet, comonomer addition port and initiator addition port, 750 g of vinyl acetate, 250 g of methanol, 1.1 g of N-octadecylmethacrylamide and 0.7 g of itaconic acid The system was purged with nitrogen for 30 minutes while bubbling nitrogen. In addition, as a delay solution, a comonomer solution in which N-octadecylmethacrylamide was dissolved in methanol to a concentration of 5% and a comonomer solution in which itaconic acid was dissolved in a methanol solution to a concentration of 25% were prepared. The solution was purged with nitrogen by bubbling nitrogen gas. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.3 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. The above delay solution was added dropwise to polymerize the monomer composition (ratio of vinyl acetate, N-octadecylmethacrylamide and itaconic acid) in the polymerization solution for 3 hours at 60 ° C., and then cooled to polymerize. Stopped. The total amount of N-octadecylmethacrylamide added until the polymerization was stopped was 4.8 g, and the total amount of itaconic acid was 9.6 g. Further, the solid content concentration at the time of termination of polymerization was 29.9%. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure to obtain a methanol solution of alkyl-itaconic acid-modified vinyl acetate polymer (alkyl-itaconic acid-modified PVAc) (concentration 35%). ) Furthermore, methanol was added to 706.9 g of an alkyl-itaconic acid-modified PVAc solution in methanol (200.0 g of alkyl-itaconic acid-modified PVAc in the solution), and 93.2 g of an alkaline solution (sodium hydroxide solution). 10% methanol solution) was added for saponification. Here, the concentration of alkyl-itaconic acid-modified PVAc in the saponification solution was 25%, and the molar ratio of sodium hydroxide to vinyl acetate units in the alkyl-itaconic acid-modified PVAc was 0.1. A gel was formed about 1 minute after the addition of the alkaline solution. The gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, 500 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. To this white solid, 2,000 g of methanol was added, and the mixture was left to wash at room temperature for 3 hours. This washing operation was repeated three times, and then the white solid obtained by centrifugal deliquoring was left in a dryer at 65 ° C. for 2 days to obtain alkyl-itaconic acid-modified PVA (PVA16).

Comparative Example 6 (Production of PVAvi)
A 3 L reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet and an initiator addition port was charged with 750 g of vinyl acetate, 250 g of methanol and 57.3 g of octadecyl vinyl ether, and the system was circulated for 30 minutes while bubbling nitrogen. Replaced with nitrogen. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 1.0 g of 2,2′-azobisisobutyronitrile (AIBN) was added to initiate polymerization. After polymerization at 60 ° C. for 2 hours, the polymerization was stopped by cooling. The solid content concentration when the polymerization was stopped was 30.4%. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 35%) of an alkyl-modified vinyl acetate copolymer (alkyl-modified PVAc). Further, 79 g of an alkyl-modified PVAc methanol solution prepared by adding methanol to 792.9 g (200.0 g of the alkyl-modified PVAc in the solution) was added to 7.0 g of an alkali solution (10% sodium hydroxide in methanol solution). Saponification was performed by adding. Here, the concentration of the alkyl-modified PVAc in the saponification solution was 25%, and the molar ratio of sodium hydroxide to the vinyl acetate unit in the alkyl-modified PVAc was 0.0075. A gel-like material was formed about 12 minutes after the addition of the alkaline solution. The gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, 500 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. To this white solid, 2,000 g of methanol was added, and the mixture was left to wash at room temperature for 3 hours. After this washing operation was repeated three times, the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain alkyl-modified PVA (PVAvi).

Comparative Example 7 (Production of PVAvii)
An alkyl-modified PVA (PVAvii) was produced in the same manner as in Comparative Example 6 except that lauryl vinyl ether was used as the unsaturated monomer having an alkyl group.

Comparative Example 8 (Production of PVAviii)
900 g of vinyl acetate and 100 g of methanol were charged into a 3 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet tube and initiator addition port, and the system was purged with nitrogen for 30 minutes while bubbling nitrogen. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 0.25 g of 2,2′-azobisisobutyronitrile (AIBN) was added to start polymerization, and polymerization was performed at 60 ° C. for 3 hours. Then, the polymerization was stopped by cooling. The solid content concentration when the polymerization was stopped was 31.0%. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution (concentration 30%) of polyvinyl acetate (PVAc). Furthermore, 27.9 g of an alkaline solution (sodium hydroxide in 10% methanol) was added to 971.1 g of PVAc methanol solution prepared by adding methanol to this solution (200.0 g of PVAc in the solution) to saponify. Went. Here, the concentration of PVAc in the saponification solution was 20%, and the molar ratio of sodium hydroxide to vinyl acetate units in PVAc was 0.03. A gel was formed about 1 minute after the addition of the alkaline solution. The gel-like material was pulverized with a pulverizer and allowed to stand at 40 ° C. for 1 hour to allow saponification to proceed. Then, 500 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, the mixture was filtered to obtain a white solid. To this white solid, 2,000 g of methanol was added, and the mixture was left to wash at room temperature for 3 hours. This washing operation was repeated three times, and then the white solid obtained by centrifugal drainage was left in a dryer at 65 ° C. for 2 days to obtain unmodified PVA (PVAviii).

The degree of polymerization, modification rate, degree of saponification, water solubility, and water resistance of the obtained PVA were evaluated by the above methods. The evaluation results are shown in Table 1.

1) In Comparative Examples 6 and 7, 1.0 g of 2,2′-azobisisobutyronitrile (AIBN) was used as a polymerization initiator. In Example 16, 0.3 g of AIBN was used. In other examples and comparative examples, 0.25 g of AIBN was used.
2) Molar ratio of sodium hydroxide (NaOH) to vinyl acetate units in alkyl-modified PVAc.
3) Polymerization using vinyl acetate, N-octadecylmethacrylamide and itaconic acid.
4) Alkyl modification rate / Itaconic acid modification rate

As shown in Table 1, the alkyl-modified PVA of the present invention is excellent in water solubility, and further has high water resistance as compared with unmodified PVA having the same degree of polymerization (Example 3, Comparative Example 8). . Furthermore, compared with the alkyl-modified PVA having the same alkyl chain length, it has high water solubility and excellent handling properties (Example 5 and Comparative Example 6). However, when the degree of saponification is low (Comparative Example 2), when the modification rate is high (Comparative Example 3), or when the alkyl chain has more than 29 carbon atoms (Comparative Example 5), there are many insolubles in the aqueous solution. confirmed. Further, the alkyl-modified PVA introduced with the monomer unit (b) having a carboxyl group is excellent in water solubility but has low water resistance (Example 16).

Examples 17 to 32 and Comparative Examples 9 to 16 (thickener and composition)
The obtained PVA was used as a thickener in Examples 17 to 32 and Comparative Examples 9 to 16, and the following evaluation was performed. Moreover, the following method evaluated the composition containing this thickener (PVA). The evaluation results are shown in Table 2.

[Thickening (viscosity of PVA aqueous solution)]
A PVA aqueous solution having a concentration of 4% was prepared by the same method as described above, and the viscosity at a temperature of 20 ° C. was measured at a rotor rotation speed of 6 rpm using a B-type viscometer.

[Thickening (thickening test of ethylene-vinyl acetate copolymer emulsion)]
100 parts of an ethylene-vinyl acetate copolymer emulsion (OM-4200NT manufactured by Kuraray Co., Ltd., concentration 55%) and 20.6 parts of a 4% concentration PVA aqueous solution (the solid content of PVA is 1. 5 parts) and 2.4 parts of water were added to prepare a mixed solution of PVA and emulsion having a concentration of 45%, and the viscosity at a temperature of 20 ° C. was measured at a rotor speed of 6 rpm using a B-type viscometer. Judged by the criteria of.
A: 10,000 mPa · s or more B: 5,000 mPa · s or more and less than 10,000 mPa · s C: 1,000 mPa · s or more and less than 5,000 mPa · s D: 500 mPa · s or more and less than 1,000 mPa · s E: <500 mPa · s

[Storage stability of ethylene-vinyl acetate copolymer emulsion]
The solution used for the thickening test was stored in a dryer at 50 ° C., the number of days required for separation of the emulsion layer and the aqueous layer was observed, and judged according to the following criteria.
A: 30 days or more B: 15 days or more and less than 30 days C: 7 days or more and less than 15 days D: 3 days or more and less than 7 days E: Less than 3 days

1) Thickening test of ethylene-vinyl acetate copolymer emulsion 2) Measurement limit of viscosity is 100,000 mPa · s
3) Polymerization using vinyl acetate, N-octadecylmethacrylamide and itaconic acid.
4) Alkyl modification rate / Itaconic acid modification rate

In Table 2, “-” indicates that PVA was not completely dissolved and was not preferable as a thickener.

As shown in Table 2, the alkyl-modified PVA contained in the thickener of the present invention has a higher viscosity than non-modified PVA having the same degree of polymerization. Therefore, the emulsion (composition) has excellent performance in terms of thickening effect and storage stability. Furthermore, compared with the alkyl-modified PVA having the same alkyl chain length (Comparative Example 14), it has high water solubility and is excellent in handleability as a thickener. However, when the number of carbon atoms of the alkyl chain exceeds 29 (Comparative Example 13), a large amount of insoluble matter remains in the aqueous solution, and it was confirmed that the alkyl chain is inappropriate as a thickener.

[Wood adhesion test]
PVAc emulsion stabilized with Kuraray's “Poval” PVA-217 (7.5 parts of PVA-217 added to 100 parts of PVAc), the above-mentioned PVA14 was added, and the total solid content was 35%, 20 An aqueous emulsion adhesive containing 4 parts of phenoxyethanol with respect to 100 parts of PVAc having a viscosity of 10,000 mPa · s at 6 ° C. was prepared.
200 g / m ^{2 of the} aqueous emulsion adhesive was applied to the rice husk material, and the same type of rice husk material was immediately bonded together and pressed at a pressure of 7 kg / cm ² for 24 hours. Thereafter, the pressure was released and the test piece was cured for 7 days at 20 ° C. and 65% RH, and 10 test pieces were prepared. The compression shear strength was measured according to JIS K-6852 using 5 test pieces. 118.3 kg / cm ² , and all the test pieces used were destroyed. Further, the remaining five test pieces were immersed in water at 30 ° C. for 3 hours, and then the compression shear strength was measured in the same manner. As a result, the adhesive strength was 21.4 kg / cm ² .

Further, when a wood adhesion test was conducted in the same manner as described above, except that PVA15 was not added and a PVAc emulsion containing 4 parts of phenoxyethanol was used alone, the adhesion strength was 113.0 kg / cm ² ( All were material destruction), 22.8 kg / cm ² .

Usually, when a urethane-based or cellulose-based compound is added to an emulsion, the water-resistant adhesive strength decreases. However, even when the alkyl-modified PVA of the present invention was added to the emulsion as described above, the water-resistant adhesive strength was hardly lowered.

Examples 33 to 48 and Comparative Examples 17 to 24 (paper coating agent)
Using the obtained PVA, paper coating agents for Examples 33 to 48 and Comparative Examples 17 to 24 were obtained by the following method. Each obtained paper coating agent was evaluated by the following methods. The evaluation results are shown in Table 3.

[Preparation of thermal paper overcoat layer]
90 g of aluminum hydroxide powder (manufactured by Showa Denko KK, Heidilite H42) was added to 210 g of distilled water and stirred manually. Thereafter, the mixture is stirred for 5 minutes at a rotational speed of 13,500 rpm using a homomixer (IKA-Labortechnik, type T-25-SI) to prepare an aluminum hydroxide dispersion (aluminum hydroxide concentration 30%). did. Separately, the obtained PVA was dissolved in 95 ° C. hot water to prepare a PVA aqueous solution having a concentration of 4%. Next, 150 g of PVA aqueous solution was added to 20 g of the above aluminum hydroxide dispersion, and both were uniformly mixed. Then, distilled water was added so that the solid concentration was 4% to obtain a coating agent. Next, the coating agent was applied to the surface of a commercially available thermal paper (manufactured by KOKUYO) with a wire bar No. After hand-painting using 60 (manufactured by ETO), the coated surface was dried at 50 ° C. for 1 hour using a hot air dryer. Next, the dried thermal paper is left in a room adjusted to 20 ° C. and 65% RH for 3 hours to determine the characteristics (water resistance and blocking resistance) of the thermal paper overcoat layer formed by the coating agent. It was set as the sample for evaluation.

[water resistant]
The sample was immersed in water at 20 ° C. for 10 minutes, and then the coated surface was rubbed 10 times with a finger to observe the state of peeling that occurred on the surface. The water resistance of the layer formed with the coating agent was evaluated in five stages according to the following criteria.
Criteria for water resistance 5: There was no peeling of the surface.
4: There was very little peeling of the surface.
3: There was some peeling of the surface.
2: There was much peeling of the surface.
1: Most of the surface was peeled off.

[Blocking resistance (surface water resistance)]
The sample was allowed to stand in an atmosphere of 40 ° C. for 72 hours and then cut into 5 cm square. Next, after dropping one drop (about 30 μL) of water on the coated surfaces, another sample on which no water droplets were dropped was stacked on the coated surfaces so that the coated surfaces were in contact with each other and allowed to dry naturally. After drying, the samples were peeled apart to observe how they were peeled off. The blocking resistance of the layer formed with the coating agent was evaluated in three stages according to the following criteria based on the observed state.
Criteria for blocking resistance 3: Naturally separated without particular force.
2: The surfaces were partially adhered to each other, but the sample was not broken.
1: The surfaces were adhered to each other, and the sample was torn by peeling.

[Preparation of inkjet recording paper]
For each obtained PVA, 1,000 g of an aqueous solution having a solid content concentration of 4% was prepared, and the aqueous PVA solution was dispersed in a gaseous solution of silica (Aerosil A300: manufactured by Nippon Aerosil Co., Ltd.) at a solid content concentration of 20%, 1,000 g. In addition, the mixture was thoroughly mixed and stirred to obtain a dispersion. Thereafter, distilled water was added to prepare a coating liquid (paper coating agent) having a solid content concentration of 12% by mass. The solution viscosity of this coating solution was measured using a B-type viscometer under conditions of a rotor rotation speed of 6 rpm and a temperature of 20 ° C., and was 100 mPa · s. On the surface of the PET film subjected to corona treatment, the above coating solution is applied at 30 ° C. using a Mayer bar so that the coating amount after drying is 15 g / m ^2, and 150 ° C. using a hot air dryer. And dried for 3 minutes to produce an ink jet recording paper.

[Evaluation of inkjet recording paper]
Ink jet recording paper was produced by the above method, and cracks of the ink receiving layer were evaluated according to the following criteria.

[crack]
The surface of the ink receiving layer was observed with an optical microscope at a magnification of 100 times, and was evaluated in five stages according to the following criteria.
5: No cracks are observed on the surface.
4: Almost no cracks are observed on the surface.
3: Cracks are partially generated on the surface.
2: Many cracks are generated on the surface.
1: Cracks occur on the entire surface.

[Preparation of release paper base paper]
A semi-glassine paper with a basis weight of 80 g / m ² and an air permeability of 140 seconds is hand-coated with a PVA aqueous solution (paper coating agent) with a concentration of 4% using a Mayer bar so that the coating amount is 0.1 g / m ^2. After coating and drying at 110 ° C. for 1 minute using a hot air dryer, humidity was adjusted at 20 ° C. and 65% RH for 72 hours, and supercalender treatment was performed at 150 ° C., 250 Kg / cm, 10 m / min. Was performed once. About the obtained release paper base paper, the air permeability test was implemented by the method shown below.

[Air permeability test of release paper base paper]
In accordance with JIS-P8117, the air permeability of the release paper base paper was measured using an Oken type lubricity air permeability tester, and evaluated in 5 stages according to the following criteria.
5: More than 50,000 seconds 4: 30,000 seconds or more, less than 50,000 seconds 3: 10,000 seconds or more, less than 30,000 seconds 2: 1,000 seconds or more, less than 10,000 seconds 1: 1, Less than 000 seconds

[Comprehensive evaluation of paper coating agents]
Comprehensive evaluation: Comprehensive evaluation was performed from the total score of the above four evaluation items, and when the evaluation result was evaluated as PVA performance, the one using PVA1 (Example 33) was 15 points. In addition, the thing with this score of 10 points or more was determined to be an acceptable product if it was less than 10 points.

1) Polymerization using vinyl acetate, N-octadecyl methacrylamide and itaconic acid.
2) Alkyl modification rate / Itaconic acid modification rate

In Table 3, “-” indicates that PVA was not completely dissolved and was not preferable as a paper coating agent.

The alkyl-modified PVA contained in the paper coating agent of the present invention is excellent in water solubility, and further has high water resistance as compared with unmodified PVA having the same degree of polymerization (Example 35, Comparative Example 24). ). Furthermore, compared with the alkyl-modified PVA having the same alkyl chain length, it has high water solubility and is excellent in handleability as a paper coating agent. (Comparative Example 22). In addition, when the degree of saponification is low (Comparative Example 18), when the alkyl modification rate is high (Comparative Example 19), or when the number of carbon atoms in the alkyl chain exceeds 29 (Comparative Example 21), insoluble matter is present in the aqueous solution. Many remained, and it was confirmed that they were unsuitable for paper coating agents.

Examples 49-64 and Comparative Examples 25-32 (Adhesive)
40 parts of each PVA described in Table 4 was added to 960 parts of ion-exchanged water at room temperature, and the temperature was raised to 95 ° C. over 1 hour while stirring. After maintaining at 95 ° C. for 2 hours, the mixture was cooled to room temperature while stirring to obtain 4% PVA aqueous solution.

These were used as the adhesives of Examples 49 to 64 and Comparative Examples 25 to 32, and the initial adhesiveness, storage stability and water resistant adhesiveness were evaluated according to the following methods. The results are shown in Table 4.

[Initial adhesion]
The initial adhesion strength was measured under the following conditions using an initial adhesion tester manufactured by Nippon Tobacco Inc.
Conditions: Kraft paper / craft paper adhesion Application speed 0.5m / sec Shear speed 300mm / sec Open time 1sec Crimping time 2sec Curing time 1sec, 3sec, 5sec, 10sec Adhesive area 1mm x 25mm x 8 locations ( 2cm ^{2 in} total)
Temperature and humidity 20 ℃, 65% RH

[Storage stability]
The state after the adhesive was allowed to stand at 40 ° C. for 7 days was observed, and the state change before and after storage was evaluated by the following indices.
A: No separation or sedimentation, no change in viscosity.
B: Slight separation and sedimentation are observed, but fluidity is present.
C: Separation and sedimentation are observed. Or there is no fluidity.

[Water-resistant adhesion]
The adhesive was coated on the kraft paper with a wire bar so that the solid content was 10 g / m ² , and the kraft paper was affixed thereon. The kraft paper was cured at 20 ° C. and 65% RH for 24 hours and then immersed in water at 30 ° C. for 30 seconds. The water of the kraft paper containing water was gently wiped off using a filter paper, and then the 180 ° peel strength of the adhesive layer was measured using an autograph and evaluated according to the following indicators.
A: Material breakage of kraft paper B: 1 kg / cm ² or more C: Less than 1 kg / cm ²

1) Polymerization using vinyl acetate, N-octadecyl methacrylamide and itaconic acid.
2) Alkyl modification rate / Itaconic acid modification rate

In Table 4, “-” indicates that PVA was not completely dissolved and was not preferable as an adhesive.

[Example 65]
To 100 parts of the 4% PVA1 aqueous solution obtained in Example 49, 8 parts of clay (Huber-900: kaolinite clay, average particle size 0.6 μm, manufactured by Huber) as a filler was added and stirred. Was sufficiently dispersed to prepare an adhesive. The solid content of the adhesive was 12.0%, and the solid content mass ratio of PVA1 to clay was 100: 200. Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 73]
Instead of the PVA1 aqueous solution, clay was added in the same manner as in Example 65 except that the PVA16 aqueous solution obtained in Example 64 was used to prepare an adhesive. The solid content of the adhesive was 12.0%, and the solid content mass ratio of PVA16 and clay was 100: 200. Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Comparative Example 33]
Clay was added in the same manner as in Example 65 except that the PVAviii aqueous solution obtained in Comparative Example 32 was used in place of the PVA1 aqueous solution to prepare an adhesive. The solid content of the adhesive was 12.0%, and the mass ratio of the solid content of PVAviii and clay was 100: 200. Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 66]
In a glass polymerization vessel equipped with a reflux condenser, dropping funnel, thermometer, nitrogen inlet, and squid type stirring blade, 450 parts of ion-exchanged water and 32 parts of PVA-117 (manufactured by Kuraray Co., Ltd.) were charged and dissolved at 95 ° C. did. Next, the PVA-117 aqueous solution was cooled, purged with nitrogen, charged with 40 parts of vinyl acetate while stirring at 140 rpm, heated to 60 ° C., and then polymerized in the presence of a redox initiator system of hydrogen peroxide / tartaric acid. Started. From 15 minutes after the start of polymerization, 360 parts of vinyl acetate was continuously added over 3 hours to complete the polymerization, and an emulsion of vinyl acetate polymer (PVAc) was obtained. The initiator used was 30 g of 1% hydrogen peroxide solution and 10 g of 5% aqueous tartaric acid solution. The solid content concentration of the obtained PVAc emulsion was 46.8%. An adhesive was prepared by mixing 100 parts of the 4% PVA1 aqueous solution obtained in Example 49 and 34.1 parts of PVAc emulsion (solid content mass ratio of PVA1 and PVAc was 100: 400). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 74]
An adhesive was prepared in the same manner as in Example 66 except that the PVA16 aqueous solution obtained in Example 64 was used instead of the PVA1 aqueous solution (the solid content mass ratio of PVA16 and PVAc was 100: 400). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Comparative Example 34]
An adhesive was prepared in the same manner as in Example 66 except that the PVAviii aqueous solution obtained in Comparative Example 32 was used instead of the PVA1 aqueous solution (the solid mass ratio of PVAviii and PVAc was 100: 400). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 67]
To 100 parts of the PVA1 aqueous solution obtained in Example 49, 8 parts of clay (Huber-900: kaolinite clay, average particle size 0.6 μm, manufactured by Huber) was added and stirred to sufficiently disperse the clay. To this dispersion, 34.1 parts of the PVAc emulsion obtained in Example 66 was added and mixed to prepare an adhesive (the solid content mass ratio of PVA1, PVAc, and clay was 100: 400: 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 75]
An adhesive was prepared in the same manner as in Example 67 except that the PVA16 aqueous solution obtained in Example 64 was used instead of the PVA1 aqueous solution (the solid mass ratio of PVA16, PVAc, and clay was 100: 400). : 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Comparative Example 35]
An adhesive was prepared in the same manner as in Example 67 except that the PVAviii aqueous solution obtained in Comparative Example 32 was used instead of the PVA1 aqueous solution (the solid mass ratio of PVAviii, PVAc, and clay was 100: 400). : 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Examples 68 and 69]
Instead of clay, calcium carbonate (Whiteon P-30, heavy calcium carbonate, average particle size 1.75 μm, manufactured by Shiroishi Kogyo Co., Ltd.) or oxidized starch (MS-3800, manufactured by Nippon Food Processing) was used. The same operations as in Example 67 were performed to obtain adhesives. Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 70]
In a glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet, 500 parts of ion-exchanged water and polyvinyl alcohol having a mercapto group at the end (M-205: polymerization degree 550, saponification degree 88.2). (Mole%, manufactured by Kuraray Co., Ltd.) 28 parts were charged and dissolved at 95 ° C. Next, 20 g of methyl methacrylate and 20 g of n-butyl acrylate were added, the temperature was raised to 65 ° C. after nitrogen substitution, and 12 g of a 1% aqueous potassium persulfate solution was added to initiate the polymerization. 180 g of methyl methacrylate and 180 g of n-butyl acrylate were continuously added. The polymerization was completed in 4 hours to obtain a methyl methacrylate / n-butyl acrylate copolymer (ACR) emulsion having a solid content concentration of 45.1% and a viscosity of 2800 mPa · s. To 100 parts of the PVA1 aqueous solution obtained in Example 49, 8 parts of clay (Huber-900: kaolinite-based clay, average particle size 0.6 μm, manufactured by Huber) was added and stirred to sufficiently disperse the clay. 35.4 parts of the emulsion was added and mixed to prepare an adhesive (PVA1, ACR and clay solid mass ratio of 100: 400: 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 71]
In place of the methyl methacrylate / n-butyl acrylate copolymer (ACR) emulsion, 29 ethylene-vinyl acetate copolymer (VAE) emulsion (OM-4200NT, solid content concentration 55.0%, manufactured by Kuraray Co., Ltd.) An adhesive was prepared in the same manner as in Example 70 except that 0.0 part was used (the solid content mass ratio of PVA1, VAE and clay was 100: 400: 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

[Example 72]
Instead of methyl methacrylate / n-butyl acrylate copolymer (ACR) emulsion, styrene-butadiene copolymer (SBR) emulsion (Nalstar SR-107, solid content concentration 48.0%, manufactured by Nippon A & L Co., Ltd.) The same operation as in Example 70 was performed except that 33.3 parts were used to prepare an adhesive (the solid content mass ratio of PVA1, SBR, and clay was 100: 400: 200). Using this, according to the said method, initial adhesiveness, storage stability, and water-resistant adhesiveness were evaluated. The results are shown in Table 5.

As shown in the results of Tables 4 and 5, the adhesive of the present invention is excellent in initial adhesiveness and storage stability. Furthermore, the saponification degree of the alkyl-modified PVA to be used, the content of the monomer unit (a) represented by the general formula (I) (alkyl modification rate), the content of the monomer unit (b) having a carboxyl group It can be seen that by adjusting the rate (itaconic acid modification rate) and the like, excellent water-resistant adhesiveness can also be exhibited.

Examples 76 to 90 and Comparative Examples 36 to 43 (film)
In the same manner as the water solubility test of PVA, PVA aqueous solutions having a concentration of 4% were prepared using the PVA listed in Table 6. Each PVA aqueous solution was cast on a PET film and then dried for 1 week under the conditions of 20 ° C. and 65% RH to obtain PVA films of Examples 76 to 90 and Comparative Examples 36 to 43, respectively. The thickness of each PVA film was 100 μm. Each obtained film was evaluated by the following methods. The evaluation results are shown in Table 6.

[Feel of film]
The tactile sensation of the obtained PVA film was compared with a film produced in the same manner using “PVA-117” manufactured by Kuraray Co., Ltd., and judged according to the following criteria.
A: Flexible as in PVA-117 B: Slightly harder and brittle than PVA-117 C: Remarkably harder and brittle than PVA-117

[Measurement of film contact angle]
The contact angle of the obtained PVA film was measured using a solid-liquid interface analyzer DropMaster500 manufactured by Kyowa Interface Science Co., Ltd., and judged according to the following criteria.
A: 90 ° or more B: 85 ° or more and less than 90 ° C: 80 ° or more and less than 85 ° D: 70 ° or more and less than 80 ° E: Less than 70 °

1) Polymerization using vinyl acetate, N-octadecyl methacrylamide and itaconic acid.
2) Alkyl modification rate / Itaconic acid modification rate

In Table 6, “-” indicates that PVA was not completely dissolved and was not preferable as a film material.

The film using the alkyl-modified PVA of the present invention has a higher contact angle with respect to water than the non-modified PVA (Example 78, Comparative Example 43). Moreover, compared with the alkyl vinyl ether modified PVA which has the same alkyl chain length, it has high water solubility and is excellent in the handleability as aqueous solution (Example 80, Comparative Example 41). However, when the degree of polymerization is low, the state of the film is poor (Comparative Example 36), and when the number of carbon atoms in the alkyl chain exceeds 29, many insolubles were confirmed in the aqueous solution (Comparative Example 40). . Further, the alkyl-modified PVA introduced with 2.0 mol% of itaconic acid units is excellent in water solubility but has a low contact angle (Example 90).

As described above, the alkyl-modified PVA of the present invention can exhibit excellent thickening properties while maintaining water solubility, and can have high water resistance in a cured state. Therefore, the alkyl-modified PVA can be suitably used for thickeners, paper coating agents, adhesives, films and the like.

The composition of the present invention is suitably used as, for example, a paper coating agent (clear coating agent, pigment coating agent, internal sizing agent, thermal paper overcoat binder, etc.), binder, adhesive, fiber paste, and the like. be able to. The thickener of the present invention can be suitably used as a thickener for use in aqueous solutions and aqueous emulsion solutions of paints, cement, concrete, binders, adhesives, cosmetics and the like. The paper coating agent of the present invention can be suitably used for the production of coated paper such as thermal paper, ink jet recording paper, release paper base paper and the like. The adhesive of the present invention is a paper adhesive used in the production or use of corrugated paper, paper bags, paper boxes, paper tubes, wallpaper, etc., wood-to-wood, wood-to-fiber, wood-to-paper, wood-to-plastics. It can be suitably used as an adhesive for woodwork to be bonded. The adhesive of the present invention can also be used for applications using fibers such as cloth and unemployed cloth, cement moldings such as concrete, various plastics, aluminum foil and the like. Furthermore, the film of the present invention can be suitably used as various water repellent coating materials, surface coating materials and the like.

Claims (17)

1. The monomer unit (a) represented by the following general formula (I) is contained, the viscosity average polymerization degree is 200 or more and 5,000 or less, the saponification degree is 20 mol% or more and 99.99 mol% or less. An alkyl-modified vinyl alcohol polymer in which the content of the body unit (a) is 0.05 mol% or more and 5 mol% or less.
   

   

   (In formula (I), R ¹ represents a linear or branched alkyl group having 8 to 29 carbon atoms. R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)
2. 2. The alkyl-modified vinyl alcohol polymer according to claim 1, wherein R ¹ in the formula (I) is a linear or branched alkyl group having 15 to 26 carbon atoms.
3. The alkyl-modified vinyl alcohol polymer according to claim 1 or 2, wherein the saponification degree is 60 mol% or more and 99.9 mol% or less.
4. Claim 1, 2, or 3 obtained by saponifying a copolymer of an unsaturated monomer represented by the following general formula (II) and a vinyl ester monomer. The alkyl-modified vinyl alcohol polymer as described.
   

   

   (In formula (II), the definitions of R ¹ and R ² are the same as in formula (I) above.)
5. The alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 4, wherein the content of the monomer unit (b) having a carboxyl group is less than 0.1 mol%.
6. A composition comprising the alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 5.
7. The composition according to claim 6, further comprising water and an oil, wherein the content of the alkyl-modified vinyl alcohol polymer with respect to 100 parts by mass of the oil is 0.1 parts by mass or more and 50 parts by mass or less.
8. A thickener comprising the alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 5.
9. The thickener according to claim 8, further comprising water or a water-containing solvent.
10. A paper coating agent comprising the alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 5.
11. A coated paper obtained by coating the paper coating agent according to claim 10 on the paper surface.
12. An adhesive comprising the alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 5.
13. The adhesive according to claim 12, further comprising, in an emulsion state, a polymer obtained from at least one monomer selected from the group consisting of an ethylenically unsaturated monomer and a diene monomer.
14. The adhesive according to claim 12 or 13, further comprising a filler.
15. The adhesive according to claim 12, 13 or 14, which is for paper or woodwork.
16. A film comprising the alkyl-modified vinyl alcohol polymer according to any one of claims 1 to 5.
17. The film according to claim 16, which has a contact angle with water of 70 ° or more.